introduction to qgis - foss4g na 2016 workshop... · exercise 1 1. on your desktop, look for the...

Introduction to QGIS

Randal Hale - NRGS

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Disclaimer:

I make no claims to any software, operating systems, companies, or programming languages.

I only lay claim to the cat pictured below.

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Data:

Data was downloaded from the State of Hawaii, Office of Planning.

● http://planning.hawaii.gov/gis/download-gis-data/

This data is not warrantied. If you use it and accidentally drive into a volcano or find an ancient tiki idol and are struck by unexplainable bad luck…..well…...you were warned.

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http://planning.hawaii.gov/gis/download-gis-data/

http://planning.hawaii.gov/gis/download-gis-data/

A Brief History……..

● Project began in 2002 as a GIS data viewer but has evolved into a fully functioning GIS Desktop that is Open Source

● Before the 2.0 release it was known as Quantum GIS and you will still hear people call it that

● Installation comes in 3 flavors - standalone and advanced for windows and packages for Linux:

● Operating Systems Supported:

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Windows Mac Linux ……...and Android

● Open Source: GNU General Public License (GPL) “which guarantees end users (individuals, organizations, companies) the freedoms to use, study, share (copy), and modify the software.[1]

[1] “GNU General Public License”. http://en.wikipedia.org/wiki/GNU_General_Public_License. Retrieved 06 November 2013

What does it do? A Lot!

● View data – vector (SHP, MapInfo, SDTS, OGR[2] Simple Features Library and more); raster (GeoTiff, IMG, ArcInfo Grid, JPEG, PNG and more – anything supported by GDAL); GRASS raster and vector data; online data served as web services (WMS, WMTS, WCS, WFS, WFS-T, etc...)

● Explore data – QGIS Browser (think ArcCatalog); on-the-fly reprojections; identify and selection tools; annotation and labeling; edit/view/search attributes; save and restore projects

● Create, edit, manage and export data – digitizing vector data (OGR and GRASS formats); create and edit SHP and GRASS data; Georeference images (with plugin); GPS data tools; visualize and download OSM data; Export to PostGIS and Spatialite Databases

[2] “GDAL: FAQ - General”. http://trac.osgeo.org/gdal/wiki/FAQGeneral. Retrieved 06 November 2013

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Intro to QGIS

I. Navigating the Interface

II. Project Configuration

III. Analysis

IV. Print Composer

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Main topics covered during the workshop

Intro to QGIS

Topics:

● QGIS Interface

● QGIS Browser

● Saving QGIS Files

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Navigating the Interface

Desktop - the main QGIS Interface will look and feel similar to ESRI’s ArcMap and several other GIS Desktop Programs.

Browser - the (data) browser can be accessed either from within Desktop as a panel or by using the Browser icon that will open a standalone version. This feature resembles ESRI's ArcCatalog except with more limited functions for reviewing data

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Exercise 1

1. On your Desktop, look for the QGIS Desktop icon and double click on it to open. It is recommended you keep QGIS open at all times going forward so you can explore the interface

Give it a moment for the splash screen to show up. Times will Vary. Most of you are used to waiting for ArcMap.

2. Close the tip screen and leave open to follow along.

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Notice that a tip screen pops up with the QGIS Desktop interface. This might provide helpful information as you are getting familiar with the program. You can turn it on/off under Settings > Options > General. Look for tips at startup.

Navigating the Interface: Desktop

QGIS interface is divided in 5 main areas: 1. Menu Bar; 2. Tool Bar; 3. Map Legend (Panel); 4. Map Canvas; 5. Status BarOther added features: 6. Manage Layers Bar; 7. Toolbox Panel; 8. Python Console

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Navigating the Interface: Layers and Navigation

● Add vector Layer

● Add Raster Layer

● Add PostGIS Layer

● Add Spatialite Layer

● Add MSSQL Spatial Layer

● Add WMS/WMTS Layer

● Add WCS Layer

● Add WFS Layer

● Add Delimited Text Layer

● New Shapefile Layer/Spatialite Layer

● Create New GPX Layer

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● Pan

● Pan Map to Selection

● Zoom In

● Zoom Out

● Zoom to Pixel Resolution

● Zoom to Full Extent

● Zoom to Selection

● Zoom to Layer

● Zoom to Last Extent

● Zoom to Next Extent

● Refresh

Navigating the Interface: Attributes

● Identify Features

● Run Feature Action

● Select Single Feature

● Deselect Features from All Layers

● Select Features using an Expression

● Open Attribute Table

● Open Field Calculator

● Measure Feature Tools

● Map Tips

● New Bookmark

● Show Bookmarks

● Annotation Tools12

Navigating the Interface: QGS Files

● QGIS can save user sessions

● Project > Save

● Save a .qgs file. Can be opened in a normal text editor13

Exercise 21. If QGIS isn’t open go ahead and open it.

2. Use the “Add Vector Layer” Tool to add the following files (under data):

● parkpts_n83.shp - Park Point Location ● parkplys_n83.shp - Park Polygon Locations ● coast_n83.shp - State Coast Polygon● hotels.shp - Hotel Point Locations

3. Use the “Add Raster Layer” Tool to add:

● Hawaii_Landsat_Mosaic_Bathymetric_Fill_c.tif - In the hawaii_landsat folder

3. Save your qgs project in the QGS directory. Call it exercise2.qgs

4. Explore the Layers Panel Toolbar:

5. You can create groups within the layers panel14

Exercise 2

6. Create a group by pushing the Highlighted icon

7. Drag and drop your park layers into the New Group

8. Name the Group Parks (right click on group and rename)

9. Save!

10. Add the <RASTER FILE> Using the Add Raster Icon

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Exercise 2

BONUS

1. Open the exercise2A.qgs file in the your qgs folder in your class data folder.

How did you fix it? In Arcmap you would get a red exclamation point next to your broken data layer.

2. Close and don’t save it. Open it in Notepad and find the line containing the landsat image (use find). Note you can fix your qgs file manually if needed. Close Notepad without saving the qgs file.

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Navigating the Interface: Desktop

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Broswer Tab

Drag and Drop onto Canvas

Right Click in Toolbar area to add browser or other panels to the Desktop

From the Manage Layers Toolbar and the Browser Panel you can add Shapefiles, Databases, WFS, WMS, and several other types of files.

Navigating the Interface: Browser

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View metadata, attributes, and a preview of vector and raster data. Also, Manage WMS connections and create new shapefiles. However, new folders must be created in Windows explorer.

Intro to QGIS



III. Analysis

IV. Print Composer

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Project Configuration

Topics:

● Settings

● Project Properties

● Coordinate Reference Systems (CRS)

● Panels, Toolbars, and Plugins

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Exercise 3

1. Open exercise2.qgs. Save it as exercise3.qgs. Go to Settings > Options

Project Configuration: Settings > Options

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Application Style, Fonts, Project File Behavior

Environment Variable for QGIS and Plugins

Feature Attributes and Table: Data Source

Vector and Raster Rendering Behaviors

Default Colors

Layer and Map Appearance

Identify and Measure Tool Settings

Defaults for Map Composer

Snapping and Digitizing Tool Settings

Raster and Pyramid Driver Options

Projection Information

Override Local Language Settings

Point to local WMS and cache settings

These change the default settings for ALL QGIS PROJECT FILES

QGIS is extremely customizable!

Project Configuration: Project Properties

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Selection color; Project Path; Map Units, Precision

On the Fly reprojection

Choose which layers are identifiable

Assign Default symbols and set transparencies

Create a WMS/WFS from a QGIS Project

Write Python Macros

Relationships (joins) within the project

These change the default project setting for the CURRENT QGIS Project

Exercise 3

1. Save exercise2.qgs as exercise3.qgs2. In exercise 3, add the haw_centerlines.shp to your QGIS session. 3. Does it line up with your imagery? 4. Right Click the Layer and go to Properties > General and look at

the Coordinate Reference System.

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Exercise 3

4. Click Cancel

5. Right click coast_83 in the Map Layers panel. Go to Properties > General and look at the Coordinate Reference System.

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Project Configuration: CRS (or Projections)

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Geographic Coordinate Systems:

Define Locations on a spherical model of the earth

Projected Coordinate Systems:

Define Locations on a flat model of the earth

Project Configuration: CRS

Geographic Coordinate Systems:

● Defines Locations with Latitude/Longitude values● Latitude runs north and south of the Equator (0° – 90° north and

south)● Longitude runs east and west of the Prime Meridian (0° - 180°)● Prime Meridian is Greenwich

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Exercise 3

6. Open the prj file for haw_centerlines in notepad (or your favorite text editor). It should look something like:

7. What do you notice about the projection ? (HINT IT’S DIFFERENT) IT HAS A PROJECTION.

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PROJCS["NAD_1983_StatePlane_Hawaii_1_FIPS_5101_Feet",GEOGCS["GCS_North_American_1983",DATUM["D_North_American_1983",SPHEROID["GRS_1980",6378137.0,298.257222101]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]],PROJECTION["Transverse_Mercator"],PARAMETER["False_Easting",1640416.666666667],PARAMETER["False_Northing",0.0],PARAMETER["Central_Meridian",-155.5],PARAMETER["Scale_Factor",0.9999666666666667],PARAMETER["Latitude_Of_Origin",18.83333333333333],UNIT["Foot_US",0.3048006096012192]]

Exercise 3

8. Right click on haw_centerlines in the Map Layer Panel and select “Save as…”

9. Save your new file to the data directory and name it hawaii_centerlines.shp

10. Make your CRS to be 26904 by clicking on the “Select CRS” button.

11. Click OK

You just reprojected a shapefile!

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Exercise 3

12. Look for your new hawaii_centerlines layer in the map layer panel. Look for it on the map.

13. Right click hawaii_centerlines and go to > Properties > General and rename the layer to Hawaii Road Centerlines

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Project Configuration: Panels, Toolbars, Plugins

Panels and Toolbars:

● Turn them on and off by going to View > Panels or Toolbars.

● Panels provide interactive“windows”. Examples: Layers,GPS Information, and toolbox

● Toolbars are a grouping of tools

● Panels/Toolbars can also be added/removed by right-clicking on the toolbar area

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Panels on top...

...Toolbars on bottom


Plugins:● Plugins are addons that introduce new features or functions to

QGIS

● Adding, removing, activating and deactivating of plugins are all done through Plugins > Manage and Install Plugins...

● Implemented as either core or external plugins

● Core Plugins (Installed) are developed by the QGIS dev team and included in distribution

● External Plugins (Get more) or 3rd Party Plugins are stored in external repositories and maintained by authors

● Within the Plugin Manager under Settings, choose Check for updates on startup and then the frequency to keep them up to date

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Useful Plugins to get you started:

● Group Stats Plugin gives you the ability to summarize data layers in tabular format● OpenLayers Plugin gives you access to open data layers to add as backdrops to your

maps. Examples include OpenstreetMap, Google Maps, Bing Maps and more.

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Exercise 4

1. Save exercise3.qgs as exercise4.qgs

2. Go to Plugins > Manage and install plugins > Plugins. Scroll down the list to find or type in search “OpenLayers Plugin”. Click and install the plugin.

3. Install the “Group Stats Plugin”. Notice you get a new icon on the desktop >

4. Go to Vector > Group Stats > Group Stats. Some of you may be familiar with the Frequency functionality in ArcGIS Desktop. You may also be familiar that it is locked by license level.

So what if you wanted to summarize some data in QGIS? You have been asked to summarize the types of Hotels in the Hawaiian Islands.

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Exercise 4

5. Open Group Stats.

6. You want to count the types of Hotels. Drag the Count Function into columns. Drag Type into Rows and Value. This will allow you to count the Types of Hotels and Display the Types in Rows.

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Exercise 4

7. Click Calculate

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Exercise 4

8. Enable the Spatial Query Plugin.

9. Select Hawaii using the select tool (hint highlight coast_n83 in your map layers).

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Exercise 4

10. Go to Vector > Spatial Query > Spatial Query

11. Select all the Hotels that fall within the island of Hawaii.

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Exercise 4

8. Take a look at the Plugins Menu. Look at Advanced Digitizing, Group Stats, Topology, Azimuth and Distance Plugin, AutoTrace, and finally Spatial Query

Note:

● Plugins can be poorly documented!● Some plugins can change your canvas projection!● Plugins extend the functionality of QGIS!● Most (if not all) are written in Python!● Sometimes they break between QGIS Upgrades! ● Overall they are a great addition to QGIS!

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Intro to QGIS



III. Analysis

IV. Print Composer

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Analysis

Topics:

● Data Layers

● Editing

● Symbolizing Layers

● Geoprocessing

○ GRASS

○ SAGA

○ GDAL

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Exercise 5

1. Open exercise4.qgs and save it as exercise5.qgs

2. Right click coast_n83 and go to properties

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Analysis: Data Layers - Vector

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Vector Layer Properties:

This provides information about the layer as well as the ability to label and customize the layer's symbology.

Join Attribute table to layer

Add/Delete Fields; edit attribute table

Create a WMS/WFS from a QGIS Project

Add Graphic overlays to layer

Metadata

Display name, source info; CRS, scaling

Layer Symbology; Transparency

Label Style and Behavior

Perform Automated tasks

Analysis: Projections

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Data projections: To jump back to projections. All Vector/Raster Data has a projection or CRS. The quickest way to check projections is to Right Click the data Layer > Properties > General

Analysis: Data Layers - Raster

Raster Layer Properties:

This provides information about the layer as well as the ability to set pyramid levels, adjust appearance, and view the histogram.

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Pyramid Resolutions

View Histogram

Display name, source info; CRS, scaling

Band and Color Rendering

Transparency Options

Metadata

Analysis: Data Formats● Vector Layer Examples (OGR

vector formats)○ ESRI Shapefile○ Spatialite (SQLite)○ GPX○ Google KML

● Raster Layers○ GeoTiff○ PNG○ JPEG○ ESRI Grid○ Erdas IMG

● Web Services● Delimited Text Layer● ESRI's Geodatabase ● Databases: Oracle, SQL Server,

PostGIS, 45

Exercise 5

1. Right click on Hawiian Road Centerlines and go to > Properties.

2. Resize or move the Layer Properties window so you can see the data in the Map Canvas. Select Style then from Saved styles, select Residential. Change the width to 0.5. Click on Apply.

3. Click on Labels and click on the box next to Label this layer with. Click on the dropdown menu next to it and select FULLNAME then click on Apply to see the change in the Map Canvas.

4. In the same Label window, click on Buffer and click on the box next to Draw text buffer. Next, go to Rendering and scroll down until you see Merge connected lines to avoid duplicate labels. Click on OK.

5. Also turn on scale-based visibility. Set the Maximum to be 24000. Hit Apply. Save your QGIS file!

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Exercise 5

6. Right Click coast_n83 and go to properties. Change the name to Coasts under the General Tab.

7. Go to the Styles Tab. Change the Fill.

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Exercise 5

8. Save The style under the style button. Save your style by going to Style > Save Style > QGIS Layer Style File

Note: When you save a style QGIS will pick that style when you add this data to a new QGIS session. It’s very similar to ArcMap’s lyr files.

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Analysis: Digitizing Tools

Digitizing Tools:

● Current Edits

● Toggle Editing

● Save Layer Edits

● Add Feature (points, lines, polygons)

● Digitize Curves

● Move Feature(s)

● Node Tool

● Delete Selected

● Cut Features

● Copy Features

● Paste Features 49

Analysis: Digitizing Tools

● Undo

● Redo

● Rotate Feature(s)

● Simplify Feature

● Add Ring

● Add Part

● Delete Part

● Reshape Feature

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● Offset Curve

● Split Features

● Merge Selected Features

● Merge Attributes of

● Selected Features

● Rotate Point Symbols

Advanced Digitizing Tools:

Exercise 6

1. Save exercise5.qgs as exercise6.qgs

2. Be sure to turn on or add Hawaii_Landsat_Mosaic_Bathymetric_Fill_c.tif to your QGIS Project.

3. Go to Layer > Create Layer -> New Spatialite Layer

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Analysis: Spatialite

SpatiaLite is an open source library intended to extend the SQLite core to support fully fledged Spatial SQL capabilities.

SQLite is intrinsically simple and lightweight:

● a single lightweight library implementing the full SQL engine● standard SQL implementation● no complex client/server architecture● a whole database simply corresponds to a single monolithic file (no

size limits)● any DB-file can be safely exchanged across different platforms,

because the internal architecture is universally portable● no installation, no configuration

SpatiaLite is smoothly integrated into SQLite to provide a complete and powerful Spatial DBMS (mostly OGC-SFS compliant).

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Exercise 6

4. Make a polygon layer!

Pick a database name

Pick a layer name

Pick a type

Pick a CRS

Add one field - it’s required

Click add attribute to list!

Click OK

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Exercise 6

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1. Large magma chamber 2. Bedrock 3. Conduit (pipe) 4. Base 5. Sill 6. Dike 7. Layers of ash emitted by the volcano 8. Flank 9. Layers of lava emitted by the volcano 10. Throat 11. Parasitic cone 12. Lava flow 13. Vent 14. Crater 15. Ash cloud

The main Volcano is Mauna Loa

Exercise 6

5. Select your crater layer in the Map Layer Panel

6. On the digitizing toolbar click “Toggle Editing”

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Exercise 6

7. Digitize a polygon around the main crater on Hawaii.

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Exercise 6

8. Once you digitize your polygon - Record a name. Click OK

9. Right click your crater layer and open the attribute table

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Analysis: Data Layers

Many Web Services such as ArcGIS Online, USGS National Map and more can be displayed if they are publicly available you you have the right address Information to the server.

QGIS supports these types of web services:

● WMS – Web Map Service● WMTS – Web Map Tile Service● WCS – Web Coverage Service● WFS – Web Feature Service● WFS-T – Web Feature Service-Transactional

Tools for these are found in the Manage Layers toolbar.

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Analysis: Vector Geoprocessing

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Analysis: Raster Processing

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Analysis: Processing ToolboxEquivalent to Spatial Analyst

Provides seamless access to multiple software tools like:

● GRASS● SAGA● GDAL● LAS TOOLS● ORFEO● QGIS Core Functionality

Processing Models can be built very similar to ArcGIS’s Model Builder

Don’t forget PYTHON!

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Intro to QGIS



III. Analysis

IV. Print Composer

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Print Composer

Topics: ● Print Composer

● Adding your Map

● Adding Map Elements

● Saving your Map

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Print Composer:

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Print Composer interface: 1. Menu Bar; 2. Tool Bar; 3. Map Layout; 4. Command History; 5. Composition; 6. Item Properties; 7. Atlas Generation

Print Composer

● Saving Map Composition

● New Composer

● Duplicate Composer

● Composer Manager

● Load From Template

● Save as Template

● Print

● Export as image

● Export as SVG

● Export as PDF

● Revert Last Change

● Restore Last Change65

● Zoom to full Extent of Map Composition

● Zoom in

● Zoom out

● Refresh Display

Print Composer

The print composer provides growing layout and printing capabilities.

● “Window” to map canvas (ESRI = data frame)● Text labels (ESRI = annotation/text elements)● Images (graphics/pictures)● Basic shape elements● Attribute tables● HTML frames● Map elements (legends, scalebars, north arrows, and title)● To open a new print composer window click Project > New Print

Composer. ● You can have as many as the QGIS project can handle!

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Print Composer: Map

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Click on Add New Map button then draw a rectangle for where the Map Canvas will appear.

Print Composer: Map Elements

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Add map elements by clicking On the icons or they are foundUnder Layout

These areas keep track of changesand allow you to customize mapElements. Atlas is similar to ESRIData Driven Pages.

Print Composer: Map Elements

Once the map has been added, decorations or elements can be added. Their properties, as well as the page properties, can be viewed and modified. The Print Composer tracks changes in the Command History window.

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Composition Tab:● Set the Page Size

● Snap to Grid

● Snap to Extents

● Map Units: Inches or MM

Item Properties Tab:● Set the Font

● Set Scale Bar Properties

● Set Legend Properties

● Set Map Element Properties

Atlas Generation Tab:● Create Automated Map

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Print Composer: Saving

The Composer Manager is accessed from both the project and Print Composer. Project > Composer Manager or Composer > Composer Manager.

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Maps saved to the QGIS project are listed in Composer Manager. New maps can be created here from either an empty composer or a template.

Exercise 7

1. Follow Along and Let’s make a map!

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Have Questions? Need Support?:

The Google is your friend! Most searches will lead you to common support resources, like:

● Mailing Lists● Forums● StackExchange● Chat● Issue Tracker● Commercial Support (NRGS is on this list!)

Find links to all the above at:

http://www.qgis.org/en/site/forusers/support.html

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Written By:

Randal Hale: [email protected]

Carol Kraemer: [email protected]

Contact Information:

http://www.northrivergeographic.com

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mailto:[email protected]

mailto:[email protected]

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